Gating circuit for a video driver including a clamping circuit

Details Gating circuit for a video driver including a clamping circuit Gating circuit for a video driver including a clamping circuit

1975-05-23

1976-10-05

Griffin, Robert L.

Facsimile and static presentation processing

Static presentation processing

Attribute control

H04N 324

Patent

active

039848647

ABSTRACT:
An amplifier for combining color difference signals with luminance signals and driving a color image reproducing device includes first and second transistors of opposite conductivity type. Color difference signals are capacitively coupled to the base of the first transistor. The emitter of the first transistor is direct current coupled to the emitter of the second transistor. Luminance signals are coupled to the base of the second transistor. Color signals developed at the collector of the first transistor are coupled to the image reproducing device. The base-emitter junction of the first transistor is also direct current coupled in feedback relation across the collector-base junction of a third transistor of like conductivity type. The emitter of the third transistor is coupled to a gating circuit which couples a reference voltage to the emitter of the third transistor to cause the third transistor to conduct during each horizontal retrace interval. As a result, the emitter of the first transistor is clamped substantially to the reference voltage to thereby determine the operating point of the first transistor. The gating circuit also selectively couples a signal to the emitter of the first transistor to render the image reproducer cut-off during the horizontal trace portion of the vertical retrace interval so that disconcerting horizontal scan lines are not visible during vertical retrace. The gating circuit is arranged so that the signal to cut off the image reproducing device during vertical retrace is disconnected from the emitter of the first transistor during the horizontal retrace intervals so as not to interfere with the clamping operation of the first and third transistors.

REFERENCES:
patent: 3436475 (1969-04-01), Zimmerman et al.
patent: 3446915 (1969-05-01), Voige
patent: 3639685 (1972-02-01), Morio
patent: 3663745 (1972-05-01), O'Toole
patent: 3763315 (1973-10-01), Norman

Affiliated with

Also associated with

Rating

Gating circuit for a video driver including a clamping circuit does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Gating circuit for a video driver including a clamping circuit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gating circuit for a video driver including a clamping circuit will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-659640